1. Field of Invention
Aspects and embodiments of the present invention are directed to the use of spectral analysis of Ventricular Fibrillation (VF) waveforms to aid in the resuscitation of a subject experiencing cardiac arrest.
2. Background
Cardiac arrest is a major cause of death worldwide. Various resuscitation efforts aim to maintain the body's circulatory and respiratory systems during cardiac arrest in an attempt to save the life of the subject. Such resuscitation efforts may include CPR (i.e., chest compressions with or without artificial respiration), defibrillation, drug therapy, open heart massage, or various combinations thereof. For many forms of cardiac arrest, such as where the subject is suffering from Ventricular Fibrillation (VF) or Ventricular Tachycardia (VT), defibrillation may be appropriate, especially if applied soon after the onset of VF or VT. However, because defibrillation can itself cause myocardial injury, it should generally be applied only when there is a sufficient probability of success that it will be successful in restoring a perfusing cardiac rhythm.
U.S. Pat. No. 5,957,856 (hereinafter the '856 patent), which is incorporated by reference in its entirety herein, discloses a system and method for predicting the success of a defibrillating shock based upon a spectral analysis of VF waveforms obtained from an electrocardiogram (ECG) of the subject. As described therein, various metrics, such as the average peak-to-trough amplitude (AM) of the VF waveform, the area of the amplitude spectrum (ASA or AMSA) of the VF waveform, the median frequency of the power spectrum of the VF waveform, or the area of the power spectrum (PSA) of the VF waveform may be used to predict when defibrillation is likely to be successful in restoring a perfusing cardiac rhythm, as well as when defibrillation is likely to not be successful.